Automobile battery charger with protection means

ABSTRACT

A device for charging storage batteries of a vehicle comprising a voltage regulator whereby the storage batteries are charged by a DC voltage obtained by rectifying an AC output voltage from an AC generator mounted on a vehicle, particularly, an automobile, so that the voltage across the storage batteries is detected thereby controlling the interruptions of an exciting current for the AC generator. Means including diodes arranged with selected polarity connections are included so as to provide paths for both overload voltages and inadvertent reverse connections of the vehicle storage battery.

United States Patent [1 1 Hwaki et al.

AUTOMOBILE BATTERY CHARGER WITH PROTECTION MEANS [75] Inventors:Katsutaro lawaki, Chiryu;

Kazumasa Mori, Kan'ya; Masaru Ishihama; Yukio Kobayashi, both of Tokyo,all of J apan [73] Assignee: Nippondensco Co., Ltd., Kariya-shi,

Aichi-ken, Japan [22] Filed: Aug. 31, 1971 [21] Appl. No.: 176,511

[52] US. Cl 320/61, 322/28, 317/33 [51] Int. Cl. H02j 7/14 [58] Field ofSearch 320/48, 61, 64;

[56] References Cited UNITED STATES PATENTS 3,332,006 7/1967 Worrell eta1. 317/33 UX June 19, 1973 Primary Examiner J. D. Miller AssistantExaminerRobert J. Hickey Att0meyCushman, Darby & Cushman [57] ABSTRACT Adevice for charging storage batteries of a vehicle comprising a voltageregulator whereby the storage batteries are charged by a DC voltageobtained by rectifying an AC output voltage from an AC generator mountedon a vehicle, particularly, an automobile, so that the voltage acrossthe storage batteries is detected thereby controlling the interruptionsof an exciting current for the AC generator. Means including diodesarranged with selected polarity connections are included so as toprovide paths for both overload voltages and inadvertent reverseconnections of the vehicle storage battery.

9 Claims, 5 Drawing Figures AUTOMOBILE BATTERY CHARGER WITH PROTECTIONMEANS BACKGROUND OF THE INVENTION 7 mobile.

2. Description of the Prior Art A conventional'device for chargingstorage batteries is as shown in FIG. 1, where numeral 1 shows an ACgenerator mounted on a vehicle, 2 an armature winding thereof, 3 anexciting winding thereof, and 4 a rectifier circuit with an externalterminal 4a connected to the positive terminal of vehicle-mountedbatteries 5. Numeral 6 shows a voltage regulator with a detectingterminal 60 connected to the positive terminal of the storage batteries5, so that the voltage across the storage batteries is detected by meansof a constant voltage diode 6b and transistors 6c and 6d are switched,controlling the interruptions of an exciting current passed through theexciting winding 3 of the AC generator, whereby the voltage generated bythe AC generator 1 is controlled to charge the storage batteries 5 whilemaintaining a constant voltage'across them. A terminal 6eof the voltageregulator 6, together with the negative terminal of the storagebatteries, is grounded. Numeral a switch 7 and a charge lamp terminal 6fof the voltage regulator 6. Numeral 9 shows an external resistorconnected parallel with the charge lamp 8.

All the resistors used with the voltage regulator 6 are made of thickfilms with resistance materials printsintered on an insulating'substrateof ceramic, and the voltage regulator 6 thereby consists of a hybridthickfilm integrated circuit.

If, due to the limited space, etc., the abovementioned conventionaldevice has to be mounted near an ignition device on an automobile, eachelement of the voltage regulator 6, especially the thick-film resistor6g tends to deteriorate, showinga'very low resistance value or a veryhigh resistance value, as the occasion may be. Thus, the voltageregulator 6 loses its normal function, resulting in overcharge orover-discharge of the storage batteries.-

To overcome these difficulties, the inventors have made an experimentalstudy and discovered that high frequency portions generated by theignition device are not absorbed by the storagebatteriesS but make theirway into the voltage regulator 6 from the input terminal 60, therebydamaging the resistor 63.

SUMMARY OF INVENTION An object of the invention is to provide a deviceforthe deterioration of each element, especially the thickfilm resistorof the voltage regulator. The deviceaccording to the invention,therefore, does not lose its functions because of an ignition pulseinduced by the ignition device, even if it is disposed in theneighborhood of the ignition device. Instead, it charges the batterieswhile always maintaining a constant voltage across them.

Another object of the invention is to provide a device for chargingstorage batteries of a vehicle whereby the storage batteries are chargedby a DC voltage obtained by rectifying an AC output voltage from an ACgenerator mountedon a vehicle so that the voltage across the storagebatteries is detected thereby controlling the interruptions of anexciting current for the AC generator by means of a transistor, theabove-described charging device further comprising a charge indicationlamp actuator circuit for detecting power generated by the AC generatorand switching the transistor to control the current to the chargeindication lamp. The positive terminal of a first diode with itsnegative terminal connected to the voltage detecting terminal of thevoltage regulator is connected to the positive terminal ofa seconddiode, while the positive terminal of the second diode is connected tothe. ground terminal of the charge indication lamp actuator circuit, thenegative terminal of the second diode being grounded.

According to the invention, an ignition pulse applied to the voltagedetecting terminal of the voltage regulator from the ignition device isbypassed to the ground through the first and second diodes to prevent itfrom being applied to the voltage regulator, thereby prevent ing theresistor, transistor and other elements' in the voltage regulator frombeing damaged by the ignition pulse.

Further, by connecting the storage batteries inversely, an excesscurrent flowing in the charge indication lamp actuator circuit and thefirst diode is blocked by the second diode, so that damage to the firstdiode, other diodes and transistor in the charge indication lampactuator circuit is'prevented. At the same time, burning of vehicleequipments as well as the vehicle itself caused by overheating of a wireharness due to the excess current can be prevented. In addition, anyabnormal event which may occur in thecharging circuitis indicated by thecharge indication lamp actuator circuit.

Also, accordingto the invention, the transistor is connected in parallelwith a third diode for bypassing an abnormal negative voltage, which isapplied to the last stage transistor of the voltage regulator, to acircuit connected with the ground. Therefore, an abnormally highnegative voltage induced by the opening and closinput terminal of avoltage regulator comprising an integrated circuit.

Since a diode is connected between a grounded terminal and an inputterminal of a voltage regulator comprising an integrated circuitaccording to the invention, an ignition pulse induced by an ignitiondevice is bypassed by means of the capacitive property of theabove-mentioned diode to a circuit connected to the ground so as toprevent the ignition pulse from being applied to an element such as athick-film resistor of the voltage regulator, whereby it is possible toprevent ing of an ignition switch is bypassed by the third diode to thecircuit connected to the ground, preventing the transistor in thevoltage regulator from being damaged by the abnormally high voltage.Further, by connecting the storage batteries inversely, a current flowsin a cir cuit leading from the diode to the negative terminal of thestorage batteries, so that a fuse in the circuit is burned to preventthe transistor and other elements in the voltage regulator from beingdamaged by the abnormal voltage.

Moreover, the device according to the invention comprises a firstresistor which doubles as a fuse and is connected between the groundterminal of the voltage regulator and the ground, and a second resistorwhich also doubles as a fuse and is connected between the groundterminal of the charge indication lamp circuit and the positive terminalof the second diode. As a result, in the event of a short circuit of thecharge indication lamp, an excess current therein causes the secondresistor to be burned out. Also, in the event of a shortcircuiting ofthe field winding of the AC generator, an excess current therein causesthe first resistor to be burned out. In this way, a current path wherethe excess current should pass is cut off, making it possible to preventthe elements including the transistor in the charge indication lampactuator circuit from being damaged.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an electric circuit diagramshowing a conventional device for charging storage batteries mounted ona vehicle.

FIG. 2 is an electric circuit diagram according to the invention showingan embodiment of the device for charging storage batteries of a vehicle.

FIGS. 3 and 4 are diagrams showing the currentvoltage characteristics ofthe diode used in the device of the invention. I

FIG. 5 is an electric circuit diagram showing another embodiment of'thedevice for charging storage batteries of a vehicle according to theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Explanation will be made now ofan embodiment of the invention with reference to the drawings. In FIG.2, similar numerals show the identical or equivalent parts as shown inFIG. 1. Numeral 611 shows a switching transistor inserted between thetransistors and 6c and6d. Numerals 6i and 6j show'diodes with theiranodes connected to each other. The cathode of the'diode 6i is connectedto the detecting terminal 6:: of the voltage regulator 6, while'thecathode of the other diode 6j is connected to the ground terminal 6e,both of the diodes 6i and 6j being integrated on the same pellet as thevoltage regulator 6. With regard tothe reverse-direction characteristicof the diodes 6i and 6j, it suffices if their breakdown voltage is suchthat they are not broken down by the voltage of the storage batteries 5.They may have a breakdown voltage higher than 100 V. Also, they may beofthe hard breakdown type as shown in FIG. .3, that is, they may beprovided with a zener characteristic, or they may be of the softbreakdown type as shown in FIG. 4. t

In the above-described construction, even if an ignition pulse inducedby the ignition device is applied to the detecting terminal 60 of thevoltage regulator 6, it is bypassed to a grounded circuit by means of acapacitive property of the diodes 6i and 6j, thereby preventing it frombeing applied to the thick-film resistor 6g "and the other elements inthe following stages. If the positive and negative terminals of thediode 6i and the lead wire are connected inversely by mistake, lack ofthe diode 6j may result in the burning of the storage batteries. Inother words, the diode 6j functions in such a manner that when thestorage batteries are connected inversely, the diode 6i and lead wireare prevented from bunning.

This invention is not limited to the above described embodiment butfinds application in various forms. For example, it may be that thecathodes of diodes 6i and 6j are connected with each other, the anode ofthe diode 6i is connected to the detecting terminal 6a of the voltageregulator 6, and the anode of the diode 6 is connected to the groundterminal 6e. Also, a single diode or constant-voltage diode may beemployed which has a characteristic similar to the combinedcharacteristic of the diodes 6i and 6j. As another alternative, aplurality of these diodes may be connected in series. The-combination ofthe diodes is not limited to that of the soft breakdown type or hardbreakdown type, but both of these types may be combined. Moreover,instead of integrating these diodes on the same pellet as the voltageregulator 6, they may be placed outside of the voltage regulator withoutrunning counter to the objects of the invention.

A second embodiment of the invention will be now explained withreference to FIG. 5. Numeral 101 shows a three-phase AC generator of thefield rotation type mounted on a vehicle, 102 an armature windingthereof, 103 a field winding thereof,-and 104 a threephase full-waverectifier circuit with its positive terminal 104a connected to the anodeof the vehiclemounted storage batteries 105. Numeral 106 shows a voltageregulator with its voltage-detecting terminal 1060 connected to thecathode of the storage batteries 105. Numeral 106b shows aconstant-voltage diode, 1060, 106d and 106a switching transistors, 106fa flywheel diode, 106g acap'acitor for removing noise,

and 10611 a feedback capacitor. Numeral 107 shows an ignition switch,108 and 109 fuses and 110 a chargeindication lamp. Numeral 111 shows acharge indication lamp actuator circuit, 112 and 113 transistors, 114and 115 diodes and 116 a resistor, the base of the transistor 112 beingconnected through the diode 115 and resistor 116 to point Acorresponding to one phase of the three-phase full-wave rectifiercircuit 104. The charge indication lamp 110 is inserted between the fuse108 and the collector of the transistor 113 included in the chargeindication lamp actuator circuit 111. An end of the field winding 103 ofthe AC generator 101'is inserted between the collector of the transistor106e of the voltage regulator 106 and the negative terminal of theflywheel diode l06f. Numeral 117 shows a first diode with its negativeterminal connected to the voltage-detecting terminal 1060 of the voltageregulator 106, while the positive. terminal thereof is connected to thepositive terminal of the second diode 1 18. The positive terminal of thesecond diode 118 is also connected to the ground terminal 111a of thecharge indication lamp actuator circuit 11 l. The negative terminal ofthe second diode 118 is grounded. Numeral 119 shows a third diodewithits negative terminal connected to the collector of the last-stagetransistor l06e of the voltage regulator 106, the positive terminalthereof being grounded. Numeral 120 shows a first resistor which doublesas'a fuse and is inserted between the ground terminal 106i of thevoltage regulator 106 and the ground. Numeral 121 shows a secondresistor which also doubles as a fuse and is connected between theground terminal 111a of the charge indication lamp actuator circuit 111and the positive terminal of the second diode 118.

The operation of the above-mentioned second embodiment will be nowexplained. The voltage regulator 106 detects by means of theconstant-voltage diode 106b a terminal voltage of the storage batteries105 which is applied to the voltage detecting terminal 106a, so that thetransistors 106e, 106d and 106e are switched to control theinterruptions of a current flow ing to the field winding 103, therebyregulating the voltage generated by the AC generator 101 to maintain aconstant voltage across the storage batteries. When a voltage at point Aof one phase of the three-phase full-wave rectifier circuit 104 isapplied to the base of transistor 112 to charge the storage batteries105 by means of a DC voltage through the full-wave rectifier circuit104, the transistor 113 of the charge indication lamp actuator circuit111 is cut off and no current flows in the charge indication lamp 110,keeping it off.

When an ignition pulse leaked from the ignition device is applied to thevoltage'detecting terminal 106::

' of the voltage regulator 106, the resistor 10612 in the input stage ofthe voltage regulator 106 may be damaged if the voltage regulator 106 isso integrated that it lacks the'diode 117. According to the invention,

however, the ignition pulse applied to the voltage detecting terminal106a exceeds forward and reverse voltages of the diodes 117 and 118 andis bypassed to a ground circuit by means of the capacitive property ofthe diodes 117 and 118 without being applied directly to the voltageregulator'106.

If the positive and negative terminals of the storage batteries 105" areconnected inversely by mistake, that is to say, if the positive andnegative terminals are grounded and connected to the voltage detectingterminal 106a respectively, lack of the diode 118 causes an excesscurrent to flow from the cathode of the storage batteries 105 throughthe ground, the grounded terminal 111a of the charge indication lampactuator circuit 111, transistor 112, diode 114 and full-wave rectifiercircuit 104 to the anode of the'storage batteries 105. In that case, anexcess current flows also from the anode of the storage batteries 105through the diode ll7'to the anode of the storage batteries 105,damaging the transistor 112 and diodes 114 and 117. According to theinvention, however, even if the anode and cathode of the storagebatteries 105 are connected inversely, the diode 118 blocks a reversecurrent which otherwise might flow to the above-described two circuitsfrom the storage batteries 105, thus preventing the transistor 112 anddiodes 114 and 117 from being damaged. Also, when the anode and cathodeof the storage batteries 105 are connected inversely, an excess currentflows in a closed loop from the cathode of the storage batteries 105through the diode 119,

I 'flywheel diode l06f, fuse 109 and ignition switch 107 to the anode,whereby the fuse 109 is burned out, thus preventing a reverse excessvoltage from being applied to the transistors 106e, 106d and 106C of thevoltage regulator 106 and the lead wire in the closed loop from beingburned.

Further, an abnormal negative voltage of several tens of volts inducedby an inductive load (not shown) as a result of opening and closing ofthe ignition key switch 107, which otherwise might be applied to thecollectors of the transistors 106e, 106d and 106( of the voltageregulator 106, is not actually applied to them but bypassed to theground through the diode 119. it is needless to say that the capacity ofthe diode 119 must be large enough to stand the abnormal negativevoltage.

Moreover, when the charge indication lamp 110 is short-circuited, anexcess current flows in a closed loop from the anode of the storagebatteries 105 to the ground through the charge indication lamp 110, the

collector and emitter of the transistor 113 of the charge indicationlamp actuator circuit 111 and the second resistor 121 which doubles as afuse. As a result, the second resistor 121 is heated and burned out,preventing the transistor 113 from being damaged, while at the same timepreventing the lead wire in the closed loop and therefore otherequipment from being burned out.

in addition, if the field winding 103 of the AC generator 101 isshort-circuited, an excess current flows in a closed loop from thecathode of the storage batteries 105 to the ground through the fieldwinding 103, the collector and emitter of the transistor 106e of thevoltage regulator 106 and the first resistor 120 which doubles as afuse, so that the first resistor 120 is heated and burned out, thuspreventing the transistor 106e from being damaged, while at the sametime preventing the lead wire in the closed loop and therefore otherequipment as well as the vehicle itself from being damaged.

In this case, the AC generator 101 stops generating power and thereforethe transistor 113 of the charge indication lamp actuator circuit 111 isenergized on receipt of a base current from the storage batteries 105,whereby the charge indication lamp is lighted, indicating that thecharging circuit is in an abnormal condition. v

, This invention is not limited to the above described embodiments butfinds application in various forms. For example, the diodes 117, 118 and119 may be replacedby a constant-voltage diode or avalanche diode withletter or reverse avalanche characteristic.

We claim:

1.-ln a device for charging storage batteries of a vehicle comprising avoltage regulator wherein said storage batteries are charged by a DCvoltage obtained by rectifying an .AC output voltage of an AC generatormounted on a vehicle and a voltage across said storage batteries isdetected thereby controlling the interruptions of an exciting current ofsaid AC generator by means of a transistor; the improvement furthercomprising a charge indication lamp actuator circuit which detects thepresence or absence of power generated by said AC generator and switchessaid transistor to control a current flow to a charge indication lamp,first and second diodes having positive and negative terminals, saidfirst diode being connected by its positive and negative terminals tothe positive terminal of the second diode and a voltage-detectingterminal of said voltage regulator respectively, the positive andnegative terminals of said second diode being connected to a groundedterminal of said charge indication lamp actuator circuit and the groundrespectively.

2. A device for charging storage batteries according to claim 1, whereina transistor in a last stage of said voltage regulator is connected inparallel with a third diode for bypassing an excess negative voltagethrough a grounded circuit, said excess negative voltage being appliedto a transistor in the last stage of said voltage regulator.

3. A device for charging storage batteries according to claim 1 furthercomprising a first resistor, which also functions as a fuse, insertedbetween the grounded terminal of said voltage regulator and the ground,and a second resistor, which also functions as a fuse, inserted betweenthe grounded terminal of said charge indication lamp actuator circuitand the positive terminal of said second diode.

' A voltage regulator system for controlling the charge of a storagebattery in a vehicle comprising:

DC generator for producing a DC voltage by rectifying an AC outputvoltage of an AC generator mounted on a vehicle;

means for connecting said DC generator to a storage switching meansconnected between said input ter- 'minal and said ground terminal andadapted for switching operation when said detecting means detects thatthe voltage of said storage battery exceeds a predetermined value,and-means for operatively connecting said switching means to said ACgenerator thereby disenabling the operation of said AC generator inresponse to said switching operation of said switching means; and

at least two diodes connected serially in reverse po-' laritywith eachother between said detecting terminal and said ground terminal; -Avoltage regulator system for controlling the charging of a storagebattery in a vehicle comprising:

DC generator for producing a DC voltage by rectifyingan AC outputvoltage of an AC generator mounted on a vehicle;

means for connecting said DC generator to a storage battery for chargingthe same and including means for connecting an anode of said battery toa ground potential;

voltage regulator comprising a detecting terminal connected to a cathodeof said battery, a ground terminal connected .to the ground potential,an input terminal connected to the cathode of said storage bzttery,means connected to said detecting terminal for detecting the voltage ofsaid storage battery, switching means connected between said inputterminal and said ground terminal and adapted for switching operation ofsaid switching means;

charge indication lamp actuator circuit comprising an input terminal, aground terminalconnected to the ground potential, means connected tosaid AC generator for detecting the operation of said AC generator, andswitching means connected between said input and ground terminals andresponsive to the detection of said detecting means for controlling theelectrical conduction between said input and ground terminals;

a charge indication lamp connected between said input terminal of saidcharge indication lamp actuator circuit and the cathode of said storagebattery; and

first and second diodes connected in series between said detectingterminal and the ground potential and in parallel with said detectingmeans of the same, said second diode having an anode connected to theanode of 'said first diode through a first junction point and a cathodeconnected to the ground potential, said first junction point beingconnected to said ground terminal of said charge indication lampactuator circuit.

6. A voltage regulator system according to claim 5 wherein said voltageregulator further comprises:

a third diode having a cathode connected to a second junction point ofsaid input terminal of said voltage regulator and said switching meansof the same and an anode connected to a third junction point of saidground terminal of said voltage regulator and the ground potential; and

a fuse connected between said input terminal of said voltage regulatorand the cathode of said storage battery.

' 7. A voltage regulator according to claim 6 further comprising: v afirst resistor which serves as a fuse connected between the groundterminal of said voltage regulator and said third junction point; and

a second resistor, which serves as a fuse connected between said firstjunction point and said second diode.

8.- A voltage regulator according to claim 4 wherein said voltageregulator further comprises:

a third diode having a ctahode connected to a second a fuse connectedbetween said input terminal of said voltage regulator and the cathode ofsaid storage battery.

9. A voltage regulator according to claim 8 further comprising:

a resistor which serves as a fuse connected between said ground terminalof said voltage regulator and said third junction point.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,7M0,637' Dated T June 19, 1973 Inventor(s) Katsutaro liwaki; Kazumase.Mori; Maseru Ishihama;

Yukio Kobayashi It is certified that: error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

in the heading Line [75] the first inven tor's name which reads "Iawehi"should read --Iwaki- Item [73] change "Nippondensco Co.,- Ltd." to

--Nj ,ppondenso 00., Ltd.i-'

Item [30] Foreign Application Priority Data I September 3, 1970 Japan..77317/70 September LL, 1970 Japan. .77900/70 Signed and sealed this20th day of November 1973.

(SEAL) Attest:

EDWARD M.FLETGILIER,JR.C Q RENE D. TEG'TIJIEYER Attesting Officer ActingCommissioner of Patents FORM PO-IOSO (10-69) USCOMM-DC 90376-P69 1* useGOVERNMENT PRINTING qmpz: nu 0-356-3 UNITED STATES PATENT OFFICEQERTEFEQATE 0F QQRRECTKON Patent No. ,7 +o,6 7 Dated T June 19; 1973Inventor(s) Katsutaro Iwaki; Kazumasa. Mori; Maseru Ishihama;

Yukio Kobayashi It is certified that. error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

in the heading Line [75] the first inventor's name which reads "Iawzki"should read mam-- Item ['73] change Nipp ncilensco Co., Ltd." to

--Nippondenso 00., Ltd- Item [30] Foreign Application Priority DataSeptember' 3, 1970 Ja an. .77317/70 September LL, 1970 Je en.........779oo/7o Signed and sealed this 20th day of November 1973.

(SEAL) Attest: I

EDWARD M.,FLETCHER,JR. RENE D. TEGTMEYER Attesting Officer ActingCommissioner of Patents FORM PO-1OSO (10-69) USCOMM-DC poems-ps9 Q USGOVERNMENT PRINTING QFFI CE I9? 0-366-334

1. In a device for charging storage batteries of a vehicle comprising a voltage regulator wherein said storage batteries are charged by a DC voltage obtained by rectifying an AC output voltage of an AC generator mounted on a vehicle and a voltage across said storage batteries is detected thereby controlling the interruptions of an exciting current of said AC generator by means of a transistor; the improvement further comprising a charge indication lamp actuator circuit which detects the presence or absence of power generated by said AC generator and switches said transistor to control a current flow to a charge indication lamp, first and second diodes having positive and negative terminals, said first diode being connected by its positive and negative terminals to the positive terminal of the second diode and a voltage-detecting terminal of said voltage regulator respectively, the positive and negative terminals of said second diode being connected to a grounded terminal of said charge indication lamp actuator circuit and the ground respectively.
 2. A device for charging storage batteries according to claim 1, wherein a transistor in a last stage of said voltage regulator is connected in parallel with a third diode for bypassing an excess negative voltage through a grounded circuit, said excess negative voltage being applied to a transistor in the last stage of said voltage regulator.
 3. A device for charging storage batteries according to claim 1 further comprising a first resistor, which also functions as a fuse, inserted between the grounded terminal of said voltage regulator and the ground, and a second resistor, which also functions as a fuse, inserted between the grounded terminal of said charge indication lamp actuator circuit and the positive terminal of said second diode.
 4. A voltage regulator system for controlling the charge of a storage battery in a vehicle comprising: a DC generator for producing a DC voltage by rectifying an AC output voltage of an AC generator mounted on a vehicle; means for connecting said DC generator to a storage battery for charging the same and including means for connecting an anode of said battery to a ground potential; a voltage regulator comprising a detecting terminal connected to a cathode of said battery, a ground terminal connected to ground potential, an input terminal connected to the cathode of said storage battery, means connected to said detecting terminal for detecting the voltage of said storage battery, switching means connected between said input terminal and said ground terminal and adapted for switching operation when said detecting means detects that the voltage of said storage battery exceeds a predetermined value, and means for operatively connecting said switching means to said AC generator thereby disenabling the operation of said AC generator in response to said switching operation of said switching means; and at least two diodes connected serially in reverse polarity with each other between said detecting terminal and said ground terminal.
 5. A voltage regulator system for controlling the charging of a storage battery in a vehicle comprising: a DC generator for producing a DC voltage by rectifying an AC output voltage of an AC generator mounted on a vehicle; means for connecting said DC generator to a storage battery for charging the same and including means for connecting an anode of said battery to a ground potential; a voltage regulator comprising a detecting terminal connected to a cathode of said battery, a ground terminal connected to the ground potential, an input terminal connected to the cathode of said storage bzttery, means connected to said detecting terminal for detecting the voltage of said storage battery, switching means connected between said input terminal and said ground terminaL and adapted for switching operation of said switching means; a charge indication lamp actuator circuit comprising an input terminal, a ground terminal connected to the ground potential, means connected to said AC generator for detecting the operation of said AC generator, and switching means connected between said input and ground terminals and responsive to the detection of said detecting means for controlling the electrical conduction between said input and ground terminals; a charge indication lamp connected between said input terminal of said charge indication lamp actuator circuit and the cathode of said storage battery; and first and second diodes connected in series between said detecting terminal and the ground potential and in parallel with said detecting means of the same, said second diode having an anode connected to the anode of said first diode through a first junction point and a cathode connected to the ground potential, said first junction point being connected to said ground terminal of said charge indication lamp actuator circuit.
 6. A voltage regulator system according to claim 5 wherein said voltage regulator further comprises: a third diode having a cathode connected to a second junction point of said input terminal of said voltage regulator and said switching means of the same and an anode connected to a third junction point of said ground terminal of said voltage regulator and the ground potential; and a fuse connected between said input terminal of said voltage regulator and the cathode of said storage battery.
 7. A voltage regulator according to claim 6 further comprising: a first resistor which serves as a fuse connected between the ground terminal of said voltage regulator and said third junction point; and a second resistor which serves as a fuse connected between said first junction point and said second diode.
 8. A voltage regulator according to claim 4 wherein said voltage regulator further comprises: a third diode having a ctahode connected to a second junction point of said input terminal of said voltage regulator and said switching means of the same and an anode connected to a third junction point of said ground terminal of said voltage regulator and the ground potential; an a fuse connected between said input terminal of said voltage regulator and the cathode of said storage battery.
 9. A voltage regulator according to claim 8 further comprising: a resistor which serves as a fuse connected between said ground terminal of said voltage regulator and said third junction point. 